Along with recent development of thin and light display devices, such as an organic electroluminescence (organic EL) device, development for a material as a semiconductor device having higher mobility of carriers (hereinafter referred to as mobility) has been demanded. Metal oxides having high mobility, such as indium, gallium, and zinc oxides, have been developed (Patent Literature 1).
Current semiconductor devices are typically made of silicon, and the process therefor requires expensive vacuum apparatuses and high-temperature process. Such semiconductor devices currently are manufactured through photolithography including a plurality of manufacturing steps, and so the manufacturing cost is high unfortunately. Then, study on another process of non-vacuum system, such as coating, also has been conducted actively to form a layer of inorganic semiconductor particles having high mobility. Study on still another process at lower temperatures also has been conducted actively to achieve the process temperature, at which a general-purpose resin substrate can be processed.
In the field of solar cells, a hetero-junction solar cell including a layer made of metal oxide on a silicon substrate is known as an existing technique. As a method for manufacturing solar cells, vacuum process, such as plasma CVD, sputter, or sputtering is used. For instance, Patent Literature 2 discloses a solar cell including a metal oxide film containing indium formed by sputtering as a semiconductor layer. On the contrary, study on non-vacuum process also has been conducted actively. Since coating as non-vacuum process to form a layer made of metal oxide particles on a silicon substrate has excellent workability and can reduce cost easily, such a method is developed actively.
Study on process at lower temperatures has been conducted actively in the field of solar cells as well to achieve the process temperature, at which a general-purpose resin substrate can be processed.